1. Field of the Invention
Embodiments of the present disclosure relate to an intermediate frequency (IF) signal loss compensation circuit, and particularly to an IF signal loss compensation circuit in an outdoor unit of a communication system.
2. Description of Related Art
Communication systems comprises transmitting signals between a transmitter and a receiver. The signals may be transmitted wirelessly or through a cable. However, there may be IF signal loss between the transmitter and the receiver when transmitting a signal via the cable.
Referring to FIG. 2, one such communication system includes an outdoor unit 20 and an indoor unit 60. The outdoor unit 20 is connected to the indoor unit 60 via a cable 40, and to an antenna 10. The cable 40 transmits IF signals and control signals between the outdoor unit 20 and the indoor unit 60. Due to loss during IF signals transmitted via the cable 40 or other devices, IF signals are attenuated, and as a result, there is a need to compensate for the IF signals loss in the cable.
Referring to FIG. 3, one such IF signal loss compensation circuit in the outdoor unit 20 includes an up converter 22, a sending amplifier 24, a down converter 26, a receiving amplifier 28, and an IF splitter 30. When the indoor unit 60 receives signals from the outdoor unit 20, radio frequency (RF) signals received from the antenna 10 are sent to the down converter 26 and is converted into IF signals, wherein the IF signals are amplified by the receiving amplifier 28 and is sent to the indoor unit 60 via the IF splitter 30. While the indoor unit 60 sends signals to the outdoor unit 20, the IF signals from the indoor unit 60 are sent to the sending amplifier 24 via the IF splitter 30 to be amplified, and then are sent to the up converter 22 and converted into RF signals. The RF signals are sent to the antenna 10. In this communication system, the sending amplifier 24 and the receiving amplifier 28 are fixed gain amplifiers and can only give IF signals loss a fixed gain compensation. Moreover, the fixed gain amplifiers cannot detect the IF signals loss in substantially real-time, consequently giving IF signals loss a variable gain compensation according to the loss.
What is needed, therefore, is an compensation circuit to remedy the above mentioned deficiencies.